X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Fkernel-consumer%2Fkernel-consumer.c;h=4e000fbd167e294c6b9139b6b7bdd2cf0098d6f1;hp=2456d3fc91936c69f074bbd038ee227c46e48220;hb=c8f59ee5fc11492ef472dc5cfd2fd2c4926b1787;hpb=536322299f7fc9ef136a0d7e50ba8e1b5d7a754b

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 2456d3fc9..4e000fbd1 100644
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -282,8 +282,19 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 	}
 	case LTTNG_CONSUMER_DATA_AVAILABLE:
 	{
-		rcu_read_unlock();
-		return -ENOSYS;
+		int32_t ret;
+		uint64_t id = msg.u.data_available.session_id;
+
+		DBG("Kernel consumer data available command for id %" PRIu64, id);
+
+		ret = consumer_data_available(id);
+
+		/* Send back returned value to session daemon */
+		ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
+		if (ret < 0) {
+			PERROR("send data available ret code");
+		}
+		break;
 	}
 	default:
 		goto end_nosignal;
@@ -472,3 +483,42 @@ error:
 	return ret;
 }
 
+/*
+ * Check if data is still being extracted from the buffers for a specific
+ * stream. Consumer data lock MUST be acquired before calling this function.
+ *
+ * Return 0 if the traced data are still getting read else 1 meaning that the
+ * data is available for trace viewer reading.
+ */
+int lttng_kconsumer_data_available(struct lttng_consumer_stream *stream)
+{
+	int ret;
+
+	assert(stream);
+
+	/*
+	 * Try to lock the stream mutex. On failure, we know that the stream is
+	 * being used else where hence there is data still being extracted.
+	 */
+	ret = pthread_mutex_trylock(&stream->lock);
+	if (ret == EBUSY) {
+		goto data_not_available;
+	}
+	/* The stream is now locked so we can do our ustctl calls */
+
+	ret = kernctl_get_next_subbuf(stream->wait_fd);
+	if (ret == 0) {
+		/* There is still data so let's put back this subbuffer. */
+		ret = kernctl_put_subbuf(stream->wait_fd);
+		assert(ret == 0);
+		pthread_mutex_unlock(&stream->lock);
+		goto data_not_available;
+	}
+
+	/* Data is available to be read for this stream. */
+	pthread_mutex_unlock(&stream->lock);
+	return 1;
+
+data_not_available:
+	return 0;
+}